HKUST Red Bird Visiting Scholars Lecture Series

New Advances on Code-Domain Non-Orthogonal Multiple Access Communications


Non-orthogonal multiple access (NOMA) is an emerging paradigm for the enabling of massive connectivity in future machine-type communications. Despite numerous research attempts in the past years, however, NOMA has not been written into 5G New Radio. In this talk, the speaker will argue that Code-Domain NOMA (CD-NOMA) is a must for the upcoming 6G. Evolving from CDMA, the multiplexing of CD-NOMA is achieved by exploiting certain structural properties of codebooks/sequences. He will introduce a number of new results on CD-NOMA transceiver design with an emphasis on sparse code multiple access (SCMA). Comparison with power-domain NOMA will also be shown.


About the Speaker

Dr. LIU Zilong has been with the School of Computer Science and Electronic Engineering, University of Essex, since December 2019, first as a Lecturer and then a Senior Lecturer since October 2023. He received his PhD from School of Electrical and Electronic Engineering, Nanyang Technological University (NTU, Singapore) in 2014, advised by Prof GUAN Yong Liang. He was a Visiting PhD student to HKUST in 2013, hosted by Prof MOW Wai Ho.

From January 2018 to November 2019, Dr. Liu was a Senior Research Fellow at the Institute for Communication Systems (ICS), Home of the 5G Innovation Centre (5GIC), University of Surrey, when he studied the air-interface design of 5G communication networks. Prior to his career in the UK, he spent nine and half years in NTU, first as a Research Associate (from July 2008 to October 2014) and then a Research Fellow (November 2014 to December 2017). His PhD thesis “Perfect- and Quasi- Complementary Sequences”, focusing on fundamental limits, algebraic constructions, and applications of complementary sequences in wireless communications, has settled a few long-standing open problems in the field.

Dr. Liu’s research lies in the interplay of coding, signal processing, and communications, with a major objective of bridging theory and practice as much as possible. Recently, he has developed an interest in advanced 6G V2X communication technologies for future connected autonomous vehicles as well as machine learning for enhanced communications and networking.

Dr. Liu is a Senior Member of IEEE and an Associate Editor of IEEE Transactions on Vehicular Technology, IEEE Transactions on Neural Networks and Learning Systems, IEEE Wireless Communications Letters, IEEE Access, Frontiers in Communications and Networks, Frontiers in Signal Processing, and Advances in Mathematics of Communications. He was a Track Co-Chair on Networking and MAC in IEEE PIMRC’2023. He was the Hosting General Co-Chair of the 10th IEEE International Workshop on Signal Design and its Applications in Communications ( and a TPC Co-Chair of the 2020 IEEE International Conference on Advanced Networks and Telecommunications Systems (ANTS’2020). He was a tutorial speaker of VTC-Fall’2021 and APCC’2021 on code-domain NOMA. He was a Consultant to the Japanese government on 6G assisted autonomous driving in 2023. Details of his research can be found at:


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